1. FIELD OF THE INVENTION
This invention relates to a process for the preparation of amphoteric resinous aqueous emulsions useful for the treatment of fiber-containing products.
2. DESCRIPTION OF THE PRIOR ART
It is well known that polyurethane resins have good elasticity, and they have heretofore been widely used in various fields as adhesives, binders for non-woven fabrics, resinous components for artificial leather products, and the like. In general, they are applied in the form of organic solvent solutions.
Ordinary fiber-treating agents such as softening agents, antistatic agents and resin processing agents are generally used in aqueous systems. Accordingly, when a polyurethane resin is to be used in combination with ordinary fiber-treating agents, it is preferred that the resin be water-soluble or that it be in the form of an aqueous emulsion.
Polyurethane resins are excellent in physical properties as elastomers, but because they contain in the molecule many hydrogen groups of carboamides, they have a large intermolecular cohesive force and the polyurethane resins are poorly soluble in non-polar solvents. Accordingly, it is very difficult to form aqueous emulsions of polyurethane resins.
It is known to prepare stable emulsions by reacting an isocyanate-terminated urethane prepolymer with an excess of a polyalkylene polyamine to form a polyurethane-urea-polyamine, and then rendering amphoteric the amino groups in the thus-formed polyurethane-urea-polyamine. The thus-formed emulsion gives a film of an excellent rubbery elasticity when dried, and it is effective as a binder for fibers, papers, leathers, woods and construction materials. However, it is insufficient in the softness which is a very important property for fibertreating agents.